SOLUTION: A mixture of 22% disinfectant solution is to be made from 15% and 25% disinfectant solutions. How much of each solution should be used if 20 gallons of the 22% solution are needed?

Question 1184881: A mixture of 22% disinfectant solution is to be made from 15% and 25% disinfectant solutions. How much of each solution should be used if 20 gallons of the 22% solution are needed?
I tried .25x+.15(20-x)=.22*20
as my equation, and got x =14. so, you would need 6 gallons of 25 and 14 of 15 but i got it wrong.
Found 2 solutions by ikleyn, MathTherapy:
Answer by ikleyn(52798) (Show Source): You can put this solution on YOUR website!
.

You correctly obtained x = 14 from your equation as a solution, but INCORRECTLY interpreted it . . . . These 14 gallons is the amount of the 25% solution. So, the answer is: 14 gallons of the 25% solution, and the rest, 20-14 = 6 gallons is the amount of the 15% solution. CHECK for the concentration : = 0.22 = 22%, the concentration of the final mixture.

Solved and explained.

Answer by MathTherapy(10552) (Show Source): You can put this solution on YOUR website!
A mixture of 22% disinfectant solution is to be made from 15% and 25% disinfectant solutions. How much of each solution should be used if 20 gallons of the 22% solution are needed?
I tried .25x+.15(20-x)=.22*20
as my equation, and got x =14. so, you would need 6 gallons of 25 and 14 of 15 but i got it wrong.

You let the amount of 25% solution to be mixed, equal to x. This then led to your equation: .25x + .15(20 - x) = .22(20)
When you solved that for x, you got 14 gallons. Remember, x represents the amount of 25% solution, NOT the amount of 15% solution.
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